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N THE MINDSET of the PAs, nothing was ever going to make the slightest dent in their convictions unless it was proven by the fossil record. And in respect of the Aquatic Theory, as one of its Valkenburg supporters commented: “It is hard to envisage precisely what form such proof might take.”

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Very hard indeed. Almost all the hominid fossils are of specimens that died by the water’s edge, and their bones sank into the silt and were thereby fossilised. In many cases they were accompanied by the remains of fish and crabs and turtles and crocodiles and the odd hippopotamus - but also by occasional land animals. The conclusion drawn from this was that one of our plains-dwelling ancestors had come to the lake or river to drink, and happened to die there. What could be more probable? They had to die somewhere, and the remains of the vast majority assumed to have died on the arid plains would have been eaten by predators or scavengers, and left no trace. It is known as “taphonomic bias.” It was and is perfectly true: the fact that their bones sank into the silt can never prove that they lived by the water. But just as certainly, it can never prove that they did not. So that settles nothing.

Then there was the nature of the fossils. Nothing about the fossils of early hominids looked aquatic. Again that is incontestable, but what would you look for? It would be just as problematic to dig up the fossil of a mustelid and ask a palaeontologist to determine whether its life-style had been that of an otter or a polecat. Pre-human fossils show clear signs of a shift towards bipedalism, and to me that spells wading. But to the orthodox, it indicates one or other of the assortment of terrestrial explanations for

walking on two legs. So altogether it looked like deadlock.

But quite unexpectedly, in the nineties, everything we had all believed about the prehistory of the African continent was turned on his head. Not all of us had accepted that our ancestors had quit the forests and moved out onto the open plains. But as far as I can remember, no-one ever questioned the fact that the open plains were there to be moved onto. Plains are as old as the hills. North America had prairies, Russia had steppes, South America had pampas, and Africa had the savannah. If a primate came down from the trees, it would naturally step out onto the grasslands.

Not necessarily. The PAs themselves were beginning to tell a new story, and part of the impetus came from a new and high-tech sector of bio-historians, the palaeopalynologists. These experts now have the ability to examine fossilised grains of pollen and tell you what kind of plant they would have turned into if they had had the chance to germinate. Other

specialists were concentrating on the remains of the smaller creatures which turned up in the same deposits as the australopithecines and other possible forefathers of humanity. All their reports pointed to the same conclusion: the areas that are now savannah were not open plains in those early days. The flora and fauna found in the same deposits as the hominids were not savannah species. At the time when the first human ancestors were walking around on two legs, their environment was covered with trees.

The revelation was very hard to adjust to. When such a firmly rooted collective belief is challenged, the reaction often resembles the one that greeted Darwin’s Origin of Species, neatly summed up in a Punch cartoon: “If this is true, let us at least hope it will not become generally known.” Journalists wanting to

make headlines out of the news were strongly discouraged. One reaction caught on film was “Just because the Savannah Theory is wrong, that doesn’t mean the Aquatic Theory is right.” There was a spate of hasty spin-doctoring. The story was presented as being about climate change. Some climate changes in Africa millions of years ago had simply been re-dated. No big deal. It was helpful that the acquisition of the new facts was cumulative, one little piece of evidence after another. So when journalists got curious about possible wider implications, it was easy to say: “But you can’t call this

news! Where did you get that idea from? No - we’ve known about this for ages.”

Another line was: “This has all been a misunder-standing. There never was a Savannah Theory - that was merely a straw man invented by Elaine Morgan. If anyone did happen to use the term savannah, they did not mean that there weren’t trees there, and woodlands, and rivers, and lakes, and maybe some forest. That would have been absurd. Perhaps woodland-savannah would have been a more precise term. But everyone knew what we meant. There’s no story here. Nothing has changed.”

But it had changed. All the explanatory power of the conventional story was derived from the concept of open grasslands. The hunter chasing the great herds, the heat of the tropical sun, their need of standing up to look over the tall grass and peer into the far horizon, their specialisation in long-distance trekking for mile after mile in the wake of the herbivores - all that thinking depended on the image of the savannah. In woodlands they would not see further through the trees by standing up. There would be no migrating herds to follow. There would be no far horizon to peer into. The long legs would not be needed for speed-running if they were dodging in and out of the trees and the undergrowth. The picture had changed utterly. But the paradigm has not changed. All the adaptations are now explained by pointing

out that even if there were trees, they might have been further apart than those in the deep forest where the other apes continued to live. Only think how how hot and sweaty they might have got when moving between one clump of trees and the next. But some of that fossilised pollen was of lianas. You do not find lianas in parklands.

In theory, every scientist should greet joyously every advance in knowledge, whether it confirms or contradicts what he had previously assumed. The PAs had stood up well to this challenge when the geneticists - the new boys on the block - had informed them that their estimate of twenty million years ago for the ape/human split had been quite wrong, and should be amended to five or six million. It was a big jump and it was disconcerting, but after a brief resistance it was accepted with good grace, even though it came from a different group of specialists. In this new case the PAs had every right to congratulate themselves on the new data. Fossil-hunters had made the discoveries, fossil-hunters had published them, and everybody was the wiser. They should have been taking a bow, instead of saying “no, no, this is of no significance”. However one of their number, Philip Tobias, did greet it with an upbeat response.

He was the doyen of South African palaeo-anthropology, a disciple of Dart, the discoverer of Homo

habilis, the custodian of the Taung skull, a zealous life-long promoter of the Savannah Theory. He

arrived in London, treating the latest turn of events as a new challenge, an exhilarating opportunity. If orthodox thinking had been on the wrong track, then of course we must go right back to the place where we went wrong, and clearly identify it, and start again from there. But virtually none of his colleagues accepted the invitation to rejoice. They had determined what line to take and Tobias was out of step.

They treated him as if he had committed a solecism.

Would I too have tried to play down the problem if I had been embedded in the system? I hope not, but I cannot be sure. The reluctance to say “I was wrong” goes pretty deep in human nature, including mine.